Peter M. Groen / CppLinuxSerial

//!
//! @file 			SerialPort.cpp
//! @author 		Geoffrey Hunter <gbmhunter@gmail.com> ()
//! @created		2014-01-07
//! @last-modified 	2017-11-23
//! @brief			The main serial port class.
//! @details
//!					See README.rst in repo root dir for more info.

#include <iostream>
#include <sstream>
#include <stdio.h>   	// Standard input/output definitions
#include <string.h>  	// String function definitions
#include <unistd.h>  	// UNIX standard function definitions
#include <fcntl.h>   	// File control definitions
#include <errno.h>   	// Error number definitions
#include <termios.h> 	// POSIX terminal control definitions (struct termios)
#include <system_error>	// For throwing std::system_error

#include "CppLinuxSerial/SerialPort.hpp"

namespace mn {
namespace CppLinuxSerial {

	SerialPort::SerialPort() :
			filePath(std::string()),
			baudRate(BaudRates::none),
			fileDesc(0)			
	{
		// Everything setup in initialiser list
	}

	SerialPort::~SerialPort()
	{

	}

	void SerialPort::SetFilePath(std::string filePath)
	{
		// Save a pointer to the file path
		this->filePath = filePath;
	}

	void SerialPort::SetBaudRate(BaudRates baudRate)
	{

		// Get current termios struct
		termios myTermios = this->GetTermios();

		switch(baudRate)
		{
			case BaudRates::none:
				// Error, baud rate has not been set yet
				throw std::runtime_error("Baud rate for '" + this->filePath + "' cannot be set to none.");
				break;
			case BaudRates::b9600:
				cfsetispeed(&myTermios, B9600);
				cfsetospeed(&myTermios, B9600);
				break;
			case BaudRates::b57600:
				cfsetispeed(&myTermios, B57600);
				cfsetospeed(&myTermios, B57600);
				break;
		}

		// Save back to file
		this->SetTermios(myTermios);

		// Setting the baudrate must of been successful, so we can now store this
		// new value internally. This must be done last!
		this->baudRate = baudRate;
	}

	void SerialPort::Open()
	{

		std::cout << "Attempting to open COM port \"" << this->filePath << "\"." << std::endl;

		if(this->filePath.size() == 0) {
			//this->sp->PrintError(SmartPrint::Ss() << "Attempted to open file when file path has not been assigned to.");
			//return false;

			throw std::runtime_error("Attempted to open file when file path has not been assigned to.");
		}

		// Attempt to open file
		//this->fileDesc = open(this->filePath, O_RDWR | O_NOCTTY | O_NDELAY);

		// O_RDONLY for read-only, O_WRONLY for write only, O_RDWR for both read/write access
		// 3rd, optional parameter is mode_t mode
		this->fileDesc = open(this->filePath.c_str(), O_RDWR);

		// Check status
		if (this->fileDesc == -1)
		{
			// Could not open COM port
		    //this->sp->PrintError(SmartPrint::Ss() << "Unable to open " << this->filePath << " - " << strerror(errno));
		    //return false;

		    throw std::system_error(EFAULT, std::system_category());
		}

		std::cout << "COM port opened successfully." << std::endl;

		// If code reaches here, open and config must of been successful

	}

	void SerialPort::EnableEcho(bool echoOn)
	{
		termios settings = this->GetTermios();
		settings.c_lflag = echoOn
					   ? (settings.c_lflag |   ECHO )
					   : (settings.c_lflag & ~(ECHO));
		//tcsetattr( STDIN_FILENO, TCSANOW, &settings );
		this->SetTermios(settings);
	}

	void SerialPort::SetEverythingToCommonDefaults()
	{
		std::cout << "Configuring COM port \"" << this->filePath << "\"." << std::endl;

		//================== CONFIGURE ==================//

		termios tty = this->GetTermios();
		/*struct termios tty;
		memset(&tty, 0, sizeof(tty));

		// Get current settings (will be stored in termios structure)
		if(tcgetattr(this->fileDesc, &tty) != 0)
		{
			// Error occurred
			this->sp->PrintError(SmartPrint::Ss() << "Could not get terminal attributes for \"" << this->filePath << "\" - " << strerror(errno));
			//return false;
			return;
		}*/

		//========================= SET UP BAUD RATES =========================//

		this->SetBaudRate(BaudRates::b57600);

		/*
		switch(this->baudRate)
		{
			case BaudRates::none:
				// Error, baud rate has not been set yet
				this->sp->PrintError(SmartPrint::Ss() << "Baud rate for \"" << this->filePath << "\" has not been set.");
				return;
			case BaudRates::b9600:
				cfsetispeed(&tty, B9600);
				cfsetospeed(&tty, B9600);
				break;
			case BaudRates::b57600:
				cfsetispeed(&tty, B57600);
				cfsetospeed(&tty, B57600);
				break;
		}*/

		//================= (.c_cflag) ===============//

		tty.c_cflag     &=  ~PARENB;       	// No parity bit is added to the output characters
		tty.c_cflag     &=  ~CSTOPB;		// Only one stop-bit is used
		tty.c_cflag     &=  ~CSIZE;			// CSIZE is a mask for the number of bits per character
		tty.c_cflag     |=  CS8;			// Set to 8 bits per character
		tty.c_cflag     &=  ~CRTSCTS;       // Disable hadrware flow control (RTS/CTS)
		tty.c_cflag     |=  CREAD | CLOCAL;     				// Turn on READ & ignore ctrl lines (CLOCAL = 1)


		//===================== (.c_oflag) =================//

		tty.c_oflag     =   0;              // No remapping, no delays
		tty.c_oflag     &=  ~OPOST;			// Make raw

		//================= CONTROL CHARACTERS (.c_cc[]) ==================//

		// c_cc[WMIN] sets the number of characters to block (wait) for when read() is called.
		// Set to 0 if you don't want read to block. Only meaningful when port set to non-canonical mode
		//tty.c_cc[VMIN]      =   1;
		this->SetNumCharsToWait(1);

		// c_cc[VTIME] sets the inter-character timer, in units of 0.1s.
		// Only meaningful when port is set to non-canonical mode
		tty.c_cc[VTIME]     =   5;          // 0.5 seconds read timeout


		//======================== (.c_iflag) ====================//

		tty.c_iflag     &= ~(IXON | IXOFF | IXANY);			// Turn off s/w flow ctrl
		tty.c_iflag 	&= ~(IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR|IGNCR|ICRNL);

		//=========================== LOCAL MODES (c_lflag) =======================//

		// Canonical input is when read waits for EOL or EOF characters before returning. In non-canonical mode, the rate at which
		// read() returns is instead controlled by c_cc[VMIN] and c_cc[VTIME]
		tty.c_lflag		&= ~ICANON;								// Turn off canonical input, which is suitable for pass-through
		tty.c_lflag		&= ~ECHO;								// Turn off echo
		tty.c_lflag		&= ~ECHOE;								// Turn off echo erase (echo erase only relevant if canonical input is active)
		tty.c_lflag		&= ~ECHONL;								//
		tty.c_lflag		&= ~ISIG;								// Disables recognition of INTR (interrupt), QUIT and SUSP (suspend) characters

		// Try and use raw function call
		//cfmakeraw(&tty);

		this->SetTermios(tty);

		/*
		// Flush port, then apply attributes
		tcflush(this->fileDesc, TCIFLUSH);

		if(tcsetattr(this->fileDesc, TCSANOW, &tty) != 0)
		{
			// Error occurred
			this->sp->PrintError(SmartPrint::Ss() << "Could not apply terminal attributes for \"" << this->filePath << "\" - " << strerror(errno));
			return;
		}*/
	}

	void SerialPort::SetNumCharsToWait(uint32_t numCharsToWait)
	{
		// Get current termios struct
		termios myTermios = this->GetTermios();

		// Save the number of characters to wait for
		// to the control register
		myTermios.c_cc[VMIN] = numCharsToWait;

		// Save termios back
		this->SetTermios(myTermios);
	}

	void SerialPort::Write(std::string* str)
	{
		if(this->fileDesc == 0)
		{
			//this->sp->PrintError(SmartPrint::Ss() << );
			//return false;

			throw std::runtime_error("SendMsg called but file descriptor (fileDesc) was 0, indicating file has not been opened.");
		}

		int writeResult = write(this->fileDesc, str->c_str(), str->size());

		// Check status
		if (writeResult == -1)
		{
			// Could not open COM port
			//this->sp->PrintError(SmartPrint::Ss() << "Unable to write to \"" << this->filePath << "\" - " << strerror(errno));
			//return false;

			throw std::system_error(EFAULT, std::system_category());
		}

		// If code reaches here than write must of been successful
	}

	void SerialPort::Read(std::string* str)
	{
		if(this->fileDesc == 0)
		{
			//this->sp->PrintError(SmartPrint::Ss() << "Read() was called but file descriptor (fileDesc) was 0, indicating file has not been opened.");
			//return false;
			throw std::runtime_error("Read() was called but file descriptor (fileDesc) was 0, indicating file has not been opened.");
		}

		// Allocate memory for read buffer
		char buf [256];
		memset (&buf, '\0', sizeof buf);

		// Read from file
		int n = read(this->fileDesc, &buf, sizeof(buf));

		// Error Handling
		if(n < 0)
		{
			// Could not open COM port
			//this->sp->PrintError(SmartPrint::Ss() << "Unable to read from \"" << this->filePath << "\" - " << strerror(errno));
			//return false;

			throw std::system_error(EFAULT, std::system_category());
		}

		if(n > 0)
		{
			//this->sp->PrintDebug(SmartPrint::Ss() << "\"" << n << "\" characters have been read from \"" << this->filePath << "\"");
			// Characters have been read
			buf[n] = '\0';
			//printf("%s\r\n", buf);
			str->append(buf);
			//std::cout << *str << " and size of string =" << str->size() << "\r\n";
		}

		// If code reaches here, read must of been successful
	}

	termios SerialPort::GetTermios()
	{
		struct termios tty;
		memset(&tty, 0, sizeof(tty));

		// Get current settings (will be stored in termios structure)
		if(tcgetattr(this->fileDesc, &tty) != 0)
		{
			// Error occurred
			std::cout << "Could not get terminal attributes for \"" << this->filePath << "\" - " << strerror(errno) << std::endl;
			throw std::system_error(EFAULT, std::system_category());
			//return false;
		}

		return tty;
	}

	void SerialPort::SetTermios(termios myTermios)
	{
		// Flush port, then apply attributes
		tcflush(this->fileDesc, TCIFLUSH);

		if(tcsetattr(this->fileDesc, TCSANOW, &myTermios) != 0)
		{
			// Error occurred
			std::cout << "Could not apply terminal attributes for \"" << this->filePath << "\" - " << strerror(errno) << std::endl;
			throw std::system_error(EFAULT, std::system_category());

		}

		// Successful!
	}

} // namespace CppLinuxSerial
} // namespace mn